The present invention relates generally to wireless communications systems and more particularly to a hooked stub collinear antenna and a method for making the same.
For a wireless communications system, an omni-directional antenna is often desirable such that the coverage area, i.e., transmission and/or reception, is generally uniform in all azimuth directions relative to the location of the antenna. As a particular example, for wireless network access points and bridges, an antenna having an omni-directional pattern with vertical polarization characteristics, a uniform horizontal plane pattern, low cross-polarization characteristics, and moderate gain, e.g., 5 to 10 decibels referenced to an isotropic radiator (5 to 10 dBi), and with greater than five percent bandwidth is desirable.
A number of approaches are commonly used to implement omni-directional antennas. More specifically, these approaches often use collinear aperture fed arrays, periodic loaded structures, or periodic sleeve dipoles. Generally, omni-directional antennas implemented using any one of these approaches include many parts, and are often fragile and difficult to manufacture. These antennas also typically have narrow bandwidths. For example, wire helix sections typically include many parts and are fragile and difficult to construct, having bandwidths less than five percent. Furthermore, wire stub sections generally have asymmetrical horizontal plane symmetry and narrow bandwidths. Approaches including a variety of periodic aperture fed or loaded structures printed on circuit board materials are easy to fabricate and are rugged. However, an omni-directional antenna using periodic aperture fed or loaded structures printed on one or more circuit boards typically lacks horizontal plane symmetry.
Thus, there exists a need for an omni-directional antenna with vertical polarization characteristics, a uniform horizontal plane pattern, low cross-polarization characteristics, and moderate gain, with greater than five percent bandwidth. Moreover, such an omni-directional antenna should be easy to manufacture.